1. Field of the Invention
The present application generally relates to a watercraft propulsion system and a control method of the system. The present application more particularly relates to a watercraft propulsion system that has an engine and a control method to control at least an operation of the engine.
2. Description of Related Art
Relatively small size watercraft can be powered by one or more outboard motors. The outboard motor normally has a propulsion device such as, for example, a propeller and an engine to power the propulsion device. The outboard motor can incorporate an air intake device that delivers air to the engine. The intake device can be provided with a throttle valve to regulate an amount of the air. The throttle valve moves between a closed position and an open position of the intake device. Normally, when the degree to which the throttle valve is opened increases, the air amount increases and the engine speed of the engine increases.
The engine, the propulsion device and the intake device, which incorporates the throttle valve, together are parts of a propulsion system of the watercraft. The propulsion system can include a control device that controls the opening degree or a position of the throttle valve. In some arrangements, the propulsion system can further include an operating unit such as, for example, a remote controller that is operated by the operator to provide a desired position of the throttle valve to the control device. Also, the propulsion system can include a valve actuator that is coupled with the throttle valve. The control device controls the valve actuator to move the throttle valve to the desired position provided by the operating unit.
The propulsion device normally is selectively operable in either forward, reverse or neutral mode. The propulsion device propels the watercraft forwardly when operating in the forward mode and propels the watercraft backwardly when operating in the reverse mode. The propulsion device does not propel the watercraft when operating in the neutral mode.
The outboard motor incorporates a changeover mechanism to change the propulsion device among the forward, reverse and neutral modes. The changeover mechanism generally is formed with a transmission that has forward and reverse bevel gears, a clutch device and a shift actuator. The shift actuator shifts the clutch device to engage the forward or reverse bevel gear such that the propulsion device operates in either the forward, reverse, or neutral mode. The operating unit can be used to provide the control device with the forward, reverse, or neutral mode of the propulsion device. In other words, the propulsion device can be set in the desired mode by the control device and the operating unit.
The control device can be connected to the valve actuator, the shift actuator and the operating unit through a network and communicate with them through the network. The network is, for example, a controller area network (CAN); a particular type of local area network (LAN).
The watercraft propulsion system described above is conventional. For example, the U.S. Pat. No. 6,273,771 discloses such a propulsion system.